The responses of Japanese encephalitis virus (JEV) mosquito vectors to 1-octen-3-ol (octenol) and CO₂ were evaluated using Centers for Disease Control (CDC) light traps at 3 sites in northern Australia. There was no significant difference between the number of Culex sitiens subgroup mosquitoes or Cx. gelidus collected in CDC light traps baited with either CO₂ alone or CO₂ octenol on Badu Island. At both mainland locations, using octenol in combination with CO₂ significantly increased collections of Cx. sitiens subgroup mosquitoes. Collections of nontarget species, such as Ochlerotatus spp., Anopheles spp., and Verrallina spp. were also significantly increased with the addition of octenol. At all 3 locations, reducing collections of nontarget mosquitoes by not using octenol increased the proportion of Culex spp. collected, thus potentially reducing the time and resources required to sort and process collections for JEV detection. Our results also indicate that trials into the efficacy of using octenol as an attractant should be carried out in each area prior to the implementation of a mosquito-based arbovirus surveillance system.